The ApoA-I mimetic peptide FAMP promotes recovery from hindlimb ischemia through a nitric oxide (NO)-related pathway

Click method preserves but EDC method compromises the therapeutic activities of the peptide-activated hydrogels for critical ischemic vessel regeneration

Peptide-functionalized hydrogel is one of commonly used biomaterials to introduce hydrogel-induced vessel regeneration. Despite many reports about the discoveries of high-active peptides (or ligands) for regeneration, the study on the conjugating methods for the hydrogel functionalization with peptides is limited. Here, we compared the vasculogenic efficacy of the peptide-functionalized hydrogels prepared by two commonly used conjugating methods, 1-ethyl-3-(3-dimethylamino propyl) carbodiimide (EDC) and Click methods, through cell models, organ-on-chips models, animal models, and RNA sequencing analysis. Two vascular-related cell types, the human umbilical vein endothelial cells (HUVECs) and the adipose-derived stem cells (ADSCs), have been cultured on the hydrogel surfaces prepared by EDC/Click methods. It showed that the hydrogels prepared by Click method supported the higher vasculogenic activities while the ones made by EDC method compromised the peptide activities on hydrogels. The vasculogenesis assays further revealed that hydrogels prepared by Click method promoted a better vascular network formation. In a critical ischemic hindlimb model, only the peptide-functionalized hydrogels prepared by Click method successfully salvaged the ischemic limb, significantly improved blood perfusion, and enhanced the functional recoveries (through gait analysis and animal behavior studies). RNA sequencing studies revealed that the hydrogels prepared by Click method significantly promoted the PI3K-AKT pathway activation compared to the hydrogels prepared by EDC method. All the results suggested that EDC method compromised the functions of the peptides, while Click method preserved the vascular regenerating capacities of the peptides on the hydrogels, illustrating the importance of the conjugating method during the preparation of the peptide-functionalized hydrogels.

Peptides as Therapeutic Agents: Challenges and Opportunities in the Green Transition Era

Peptides are at the cutting edge of contemporary research for new potent, selective, and safe therapeutical agents. Their rise has reshaped the pharmaceutical landscape, providing solutions to challenges that traditional small molecules often cannot address. A wide variety of natural and modified peptides have been obtained and studied, and many others are advancing in clinical trials, covering multiple therapeutic areas. As the demand for peptide-based therapies grows, so does the need for sustainable and environmentally friendly synthesis methods. Traditional peptide synthesis, while effective, often involves environmentally draining processes, generating significant waste and consuming vast resources. The integration of green chemistry offers sustainable alternatives, prioritizing eco-friendly processes, waste reduction, and energy conservation. This review delves into the transformative potential of applying green chemistry principles to peptide synthesis by discussing relevant examples of the application of such approaches to the production of active pharmaceutical ingredients (APIs) with a peptide structure and how these efforts are critical for an effective green transition era in the pharmaceutical field.

Chrysin promotes angiogenesis in rat hindlimb ischemia: Impact on PI3K/Akt/mTOR signaling pathway and autophagy

Limb ischemia occurs due to obstruction of blood perfusion to lower limbs, a manifestation that is associated with peripheral artery disease (PAD). Angiogenesis is important for adequate oxygen delivery. The present study investigated a potential role for chrysin, a naturally occurring flavonoid, in promoting angiogenesis in hindlimb ischemia (HLI) rat model. Rats were allocated into four groups: (1) sham-operated control, (2) HLI: subjected to unilateral femoral artery ligation, (3) HLI + chrysin: received 100 mg/kg, i.p. chrysin immediately after HLI, and (4) HLI + chrysin + rapamycin: received 6 mg/kg/day rapamycin i.p. for 5 days then subjected to HLI and dosed with 100 mg/kg chrysin, i.p. Rats were killed 18 h later and gastrocnemius muscles were collected and divided into parts for (1) immunohistochemistry detection of CD31 and CD105, (2) qRT-PCR analysis of eNOS and VEGFR2, (3) colorimetric analysis of NO, (4) ELISA estimation of TGF-β, VEGF, ATG5 and Beclin-1, and (5) Western blot analysis of p-PI3K, PI3K, p-Akt, Akt, p-mTOR, mTOR, and HIF-1α. Chrysin significantly enhanced microvessels growth in HLI muscles as indicated by increased CD31 and CD105 levels and decreased TGF-β. Chrysin's proangiogenic effect is potentially mediated by increased VEGF, VEGFR2 and activation of PI3K/AKT/mTOR pathway, which promoted eNOS and NO levels as it was reversed by the mTOR inhibitor, rapamycin. Chrysin also inhibited autophagy as it decreased ATG5 and Beclin-1. The current study shows that chrysin possesses a proangiogenic effect in HLI rats and might be useful in patients with PAD.

Anti-atherosclerotic effects of an improved apolipoprotein A-I mimetic peptide

BACKGROUND

Apolipoprotein (Apo)A-I is a major protein component of high-density lipoprotein (HDL) that causes cholesterol efflux from peripheral cells through ATP-binding cassette transporter A1 (ABCA1) and the generation of HDL. Furthermore, it has a possible protective function against atherosclerotic cardiovascular disease (ASCVD). We previously developed a novel ApoA-I mimetic peptide without phospholipids (Fukuoka University ApoA-I Mimetic Peptide, FAMP). According to our previous studies, FAMP had an anti-arteriosclerotic effect. Since the required dose and reaction time of conventional FAMP were relatively large and short, respectively, we newly developed an improved FAMP (i-FAMP).

METHODS AND RESULTS

We synthesized four candidate i-FAMPs, i-FAMP-D1, -D2, -D3 and -D4, and examined which i-FAMP has greater cholesterol efflux capacity than FAMP in A172 human glioblastoma cells transiently transfected with human ABCA1 cDNA. Only i-FAMP-D1 showed significantly greater cholesterol efflux capacity than conventional FAMP. i-FAMP-D1 formed stronger α-helical conformations than FAMP as assessed by circular dichroism spectra. Thus, we selected i-FAMP-D1 for further experiments. i-FAMP-D1 had a greater atheroprotective effect than FAMP in ApoE knockout mice. In addition, i-FAMP-D1 activated cholesterol efflux from macrophage to HDL more strongly than FAMP and increased cholesterol excretion from liver to feces.

CONCLUSION

These results suggest that i-FAMP-D1 has a stronger anti-atherosclerotic effect than conventional FAMP.

Effect of Diallyl Trisulfide on Ischemic Tissue Injury and Revascularization in a Diabetic Mouse Model

BACKGROUND AND OBJECTIVE

Allitridin [diallyl trisulfide (DATS)] is an extract from garlic (Allium sativum) that putatively improves endothelial function and is protective against cardiovascular diseases. Endothelial dysfunction after tissue ischemia in diabetic patients is partially due to poor angiogenic response. This study investigated whether DATS may improve angiogenesis in a diabetic mouse model with hind limb ischemia.

METHODS

Streptozotocin was administered by intraperitoneal injection to establish the model of diabetes in male C57BL/6 mice. After 14 days, nondiabetic and diabetic mice (n = 24, each) underwent unilateral hind limb ischemia by femoral artery ligation. The mice were apportioned to 4 groups: nondiabetic treated (or not) with DATS and diabetic treated (or not) with DATS. DATS treatment consisted of a single daily intraperitoneal injection of 500 μg·kg·d for 14 days, beginning on the day of induced ischemia. Ischemia was scored by standard criteria. Blood perfusion was determined using thermal infrared imaging. Tissue capillary density and oxidative stress levels were measured by immunohistochemistry and immunofluorescence, respectively. Serum lipids were measured by enzymatic colorimetric assay. Fasting serum insulin was detected using an insulin enzyme-linked immunosorbent assay kit. Nitric oxide (NO) metabolites and protein carbonyls in tissues were determined by enzyme-linked immunosorbent assay. Targeted protein concentrations were measured by western blotting.

RESULTS

At 14 days after ligation, the ischemic skeletal muscle of the streptozotocin-induced diabetic mice had lower levels of endothelial NO synthase, phosphorylated endothelial NO synthase, and vascular endothelial growth factor compared with nondiabetic group. In addition, the hind limb blood perfusion, capillary density, and NO bioactivity were lower in the diabetic group, whereas oxidative stress and protein carbonyl levels were higher. These changes were ameliorated by DATS treatment.

CONCLUSIONS

DATS treatment of diabetic mice promoted revascularization in ischemic tissue.